In this paper we analyze the effects of certain sociocultural and envi
ronmental factors (migration, insufficiency of resources, social confl
ict) on the health, morbidity, growth, and adaptation of a human popul
ation from Northern Spain. Our study was centered on a 9th-century med
ieval population in the Basque Country, Los Castros de Lastra (hencefo
rth ''Los Castros''). The area in which this population settled suffer
ed intense social conflict during the Muslim occupation of the Iberian
Peninsula. The dental pathologies encountered, along with stress indi
cators (enamel hypoplasia, cribra orbitalia, growth of the long bones)
show frequencies in Los Castros different from those of other populat
ions. This skeletal evidence can be directly related to environmental
factors. Particularly important among such conditions are scarcity of
resources in a desolate land, the fact that the population had been re
cently settled, and the persistent sociopolitical conflict.